n8n 3.0 removed the HTTP Request Tool: call Sume from an agent

On n8n 3.0 the legacy HTTP Request Tool no longer exists, so an agent that called Sume through it needs a replacement. The n8n 3.0 breaking-changes page says to use the regular HTTP Request node connected to the Tool input of the AI Agent node. The other option is to point the agent at Sume's hosted remote MCP server, which exposes the tools directly.

The two replacement paths

Both paths keep the agent in charge of when to generate. They differ in who owns the request shape.

Path one: a fixed HTTP Request tool

Create the node, set the method to POST and the URL to the Sume endpoint you intend to expose, and add an Authorization: Bearer header from an n8n credential. Add an Idempotency-Key header. Without it, an agent retry after a tool error can create a second paid job.

Describe the tool narrowly. A single Format run endpoint with an output_schema is easier for a model to call correctly than a general generation route. Format runs accept generation_spend_cap_usd, which puts a ceiling on one run.

Path two: hosted MCP

Sume's hosted server is a streamable HTTP endpoint at https://mcp.sume.com/mcp. An API key sent as Authorization: Bearer or x-api-key sees the full tool set. Write and paid tools require an idempotency_key, and accept optional dry_run and max_spend_usd, so the agent can price a call before it commits.

Long jobs matter here too. jobs_wait holds for at most 55 seconds per call. If it returns wait_slice_expired, call it again with the same ids rather than resubmitting the create.

• Use tools_list and tools_schema first so the agent sees real argument names.
• A 524 or 522 from a proxy is a transport failure, not a job outcome.
• OAuth tokens are not API keys; pick one auth style per client.

What to test after migrating

Run the agent twice with the same request and confirm the second call returns the original job rather than a new one. Then force a tool error and confirm the agent does not loop on paid creates. Finally check that your n8n instance can reach the Sume host, since 3.0 also widens the SSRF blocklist to include 100.64.0.0/10.